An airbag module basically consists in a folded bag that inflates quickly through gas produced by a generator when certain sensor devices detect a vehicle collision. This way the bag unfolds between the vehicle occupant and a part of the vehicle, protecting the occupant during a collision.
During normal operation of bag unfolding, the internal pressure produced by the generator on filling it with gas can be sufficiently high to make the bag so hard that the occupant bounces back. In order to avoid this inconvenience they are provided with a ventilation orifice that serves to reduce pressure inside the bag and, therefore, the possibility of causing damages when they are activated.
Furthermore, several methods have been used to close this ventilation orifice in order to improve pressure control inside the bag than that offered by the variation in size of the hole. In this sense, it is worth highlighting the use of patches to ensure the gas is not immediately released through the discharge orifice, but when the patch breaks on reaching a certain pressure inside the bag. The technology has proposed different types of patches with different means to control their breaking depending, to a greater or lesser extent, on a given resistance to gas pressure inside the bag. This makes the presence of gas pressure necessary for the bag to fulfil its protection function compatible with the guarantee that the gas pressure shall not be excessive, with the consequent risk to persons the bag unfolds for.
In addition, the need for some ventilation devices has emerged that allow increasing the flow of gas out depending on specific characteristics of each collision and the type of passenger affected, and in this sense there are several solutions of ventilation devices that offer adjustable surface ventilation orifices to increase the ventilation area as the interior pressure increases in the bag.
A new requirement proposes the need of airbags that can reduce the ventilation area, even eliminating it completely, under certain impact conditions, which requires sealing mechanisms that must work opposite to that indicated. Traditional patches, mentioned above, should completely cover the outlet orifice until the gas pressure inside bag reached a certain level and then broke; now the opposite is required: devices that can cover the ventilation orifice under certain situations. We know of some proposals on this matter such as:
Patent ES 2182629, U.S. Pat. No. 6,139,048, patent request US 2004/0090054, patent request WO 2006/024472 and patent request US 2006/0151979 describe devices that use movable elements to seal a ventilation orifice maximizing tensions produced in the bag due to the difference in pressure next to the difference in the form of occupant load.
Patent requests EP 1 640 221 and WO 2007/003418 describe passive mechanisms for ventilation control using elements that seal the ventilation orifice in the event of certain conditions.
An inconvenience of the aforementioned proposals is that they lack sufficient adaptive capacity for different crash configurations.
This invention is targeted to resolve this inconvenience.